U.S. patent application number 11/626420 was filed with the patent office on 2007-09-20 for three clutch powershift transmission.
This patent application is currently assigned to MAGNA POWERTRAIN USA, INC.. Invention is credited to John R. Forsyth.
Application Number | 20070214903 11/626420 |
Document ID | / |
Family ID | 38516359 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070214903 |
Kind Code |
A1 |
Forsyth; John R. |
September 20, 2007 |
Three Clutch Powershift Transmission
Abstract
An automated triple-clutch multi-speed transmission is adapted
to transfer power from the engine to the driveline of a motor
vehicle. The transmission includes a first clutch operable for
establishing a releasable drive connection between an input shaft
and a first shaft, a second clutch operable for establishing a
releasable drive connection between the input shaft and a second
shaft and a third clutch operable for establishing a releasable
drive connection between the input shaft and a third shaft. A first
constant mesh gearset is driven by the first shaft. A second
constant mesh gearset is driven by the second shaft. A third
constant mesh gearset is driven by the third shaft. First, second
and third gearset clutches are operable for releasably drivingly
coupling the first, second and third gearsets to a countershaft
which, in turn, drives an output shaft.
Inventors: |
Forsyth; John R.; (Romeo,
MI) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
MAGNA POWERTRAIN USA, INC.
Troy
MI
|
Family ID: |
38516359 |
Appl. No.: |
11/626420 |
Filed: |
January 24, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60783192 |
Mar 16, 2006 |
|
|
|
Current U.S.
Class: |
74/325 |
Current CPC
Class: |
Y10T 74/19228 20150115;
F16H 3/0915 20130101; Y10T 74/19219 20150115; F16H 3/006 20130101;
F16H 2200/0052 20130101; Y10T 74/19223 20150115 |
Class at
Publication: |
74/325 |
International
Class: |
F16H 3/08 20060101
F16H003/08 |
Claims
1. A triple-clutch transmission for use in a motor vehicle having
an engine and a driveline, comprising: an input shaft continuously
driven by the engine; an output shaft adapted for connection to the
driveline and having a first output gear fixed thereto; a
countershaft having a second output gear fixed thereto in meshed
engagement with the first output gear; a first clutch operable for
establishing a releasable drive connection between the engine and a
first substantially tubular shaft having a first drive gear fixed
thereto, the first tubular shaft concentrically encompassing a
portion of the input shaft; a second clutch operable for
establishing a releasable drive connection between the input shaft
and a second substantially tubular shaft, the second tubular shaft
concentrically encompassing a portion of the output shaft and
having a second drive gear fixed thereto; a third clutch operable
for establishing a releasable drive connection between the input
shaft and a third substantially tubular shaft, the third tubular
shaft concentrically encompassing a portion of the input shaft and
having a third drive gear fixed thereto; first, second and third
speed gears rotatably supported on the countershaft, the first
speed gear being in meshed engagement with the first drive gear,
the second speed gear being in meshed engagement with the second
drive gear and the third speed gear being in meshed engagement with
the third drive gear; and first, second and third speed gear
clutches, the first speed gear clutch operable for releasably
drivingly coupling the first speed gear and the countershaft, the
second speed gear clutch operable for releasably drivingly coupling
the second speed gear and the countershaft, the third speed gear
clutch operable for releasably drivingly coupling the third speed
gear and the countershaft.
2. The triple-clutch transmission of claim 1 further including a
controller for controlling actuation of the first, second and third
clutches.
3. The triple-clutch transmission of claim 2 further including
first, second and third actuators controlling the first, second and
third clutches, respectively, the controller controlling actuation
of the first, second and third actuators.
4. The triple-clutch transmission of claim 2 wherein the first,
second and third speed gear clutches are power-operated dog
clutches, and wherein the controller is operable to control
actuation of the first, second and third speed gear clutches.
5. The triple-clutch transmission of claim 1 wherein the second and
third clutches each include clutch plates in engagement with a
common drum that is fixed for rotation with the input shaft.
6. The triple-clutch transmission of claim 5 wherein the second
clutch includes a clutch pack disposed between the drum and the
second tubular shaft.
7. The triple-clutch transmission of claim 6 wherein the third
clutch includes a clutch pack disposed between the drum and the
third tubular shaft.
8. The triple-clutch transmission of claim 1 further including
fourth, fifth and sixth speed gears rotatably supported on the
countershaft, a fourth drive gear fixed to the first tubular shaft
and meshed with the fourth speed gear, a fifth drive gear fixed to
the second tubular shaft and meshed with the fifth speed gear, and
a sixth drive gear fixed to the third tubular shaft and meshed with
the sixth speed gear.
9. The triple-clutch transmission of claim 8 wherein the first
speed gear clutch is operable for releaseably drivingly coupling
the fourth speed gear to the countershaft, the second speed gear
clutch is operable for releaseably drivingly coupling the fifth
speed gear to the countershaft, and the third speed gear clutch is
operable for releaseably drivingly coupling the sixth speed gear to
the countershaft.
10. The triple-clutch transmission of claim 1 wherein the second
and third clutches are axially positioned between drive gears fixed
to the second tubular shaft and the third tubular shaft.
11. The triple-clutch transmission of claim 1 wherein the first,
second and third clutches are normally closed clutches operable to
transmit torque without an application of external force.
12. A triple-clutch transmission for use in a motor vehicle having
an engine and a driveline, comprising: an input shaft continuously
driven by the engine; an output shaft adapted for connection to the
driveline; a countershaft in constant driving engagement with the
output shaft; a first clutch operable for establishing a releasable
drive connection between the input shaft and a first shaft; a
second clutch operable for establishing a releasable drive
connection between the input shaft and a second shaft; a third
clutch operable for establishing a releasable drive connection
between the input shaft and a third shaft; a first constant mesh
gearset driven by the first shaft; a second constant mesh gearset
being driven by the second driven shaft; a third constant mesh
gearset driven by the third shaft; and first, second and third
gearset clutches, the first gearset clutch operable for releasably
drivingly coupling the first gearset and the countershaft, the
second gearset clutch operable for releasably drivingly coupling
the second gearset and the countershaft, and the third gearset
clutch operable for releasably drivingly coupling the third gearset
and the countershaft.
13. The triple-clutch transmission of claim 12 further including a
fourth gearset driven by the first shaft, a fifth gearset driven by
the second shaft, and a sixth gearset driven by the third
shaft.
14. The triple-clutch transmission of claim 13 wherein the first
gearset clutch is operable to releasably drivingly couple the
fourth gearset and the countershaft, the second gearset clutch is
operable to releasably drivingly couple the fifth gearset and the
countershaft, and the third gearset clutch is operable to
releasably drivingly couple the sixth gearset and the
countershaft.
15. The triple-clutch transmission of claim 14 further including a
reverse gearset driven by the first shaft and a fourth gearset
clutch operable for releasably drivingly coupling the reverse
gearset and the countershaft.
16. The triple-clutch transmission of claim 12 wherein the first
shaft concentrically encompasses a portion of the input shaft.
17. The triple-clutch transmission of claim 16 wherein the second
shaft concentrically encompasses a portion of the output shaft.
18. The triple-clutch transmission of claim 16 wherein the third
shaft concentrically encompasses a portion of the input shaft.
19. The triple-clutch transmission of claim 12 further including a
controller for controlling actuation of the first, second and third
clutches.
20. The triple-clutch transmission of claim 19 further including
first, second and third actuators controlling the first, second and
third clutches, respectively, the controller controlling actuation
of the first, second and third actuators.
21. The triple-clutch transmission of claim 20 wherein the first,
second and third gearset clutches are power-operated dog clutches
and the controller is operable for controlling actuation
thereof.
22. The triple-clutch transmission of claim 21 wherein each of the
first, second and third clutches include multi-plate clutch
packs.
23. The triple-clutch transmission of claim 12 wherein the first,
second and third clutches are normally closed clutches operable to
transmit torque without an application of external force.
Description
CROSS REFERENCE
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 60/783,192 filed Mar. 16, 2006, the entire
disclosure of which is incorporated by reference
FIELD
[0002] The present disclosure relates to transmissions for use in
motor vehicles and, more particularly, to a triple-clutch automated
transmission applicable for use in motor vehicles.
BACKGROUND
[0003] Automobile manufacturers continuously strive to improve fuel
efficiency. This effort to improve fuel efficiency, however, is
typically offset by the need to provide enhanced comfort and
convenience to the vehicle operator. For example, it is well known
that manual transmissions are more fuel efficient than automatic
transmissions, yet a majority of all passenger vehicles are
equipped with automatic transmissions due to the increased
convenience they provide.
[0004] More recently, "automated" variants of conventional manual
transmissions have been developed which shift automatically without
any input from the vehicle operator. Such automated transmissions
typically include a plurality of power-operated actuators that are
controlled by a transmission controller to shift traditional
synchronized dog clutches. However, such automated transmissions
have the disadvantage that there is a power interruption in the
drive connection between the input shaft and the output shaft
during sequential gear shifting. Power interrupted shifting results
in a harsh shift feel which is generally considered to be
unacceptable when compared to the smooth shift feel associated with
most automatic transmissions. To overcome this problem, automated
twin-clutch transmissions have been developed which can be
powershifted to permit gearshifts to be made under load. Examples
of such automated manual transmissions are shown in U.S. Pat. Nos.
5,966,989 and 5,890,392. While such powershift twin-clutch
transmissions overcome several drawbacks associated with
conventional single-clutch automated transmissions, a need exists
to develop simpler and more robust transmissions which advance the
automotive transmission technology.
SUMMARY
[0005] Accordingly, the present invention provides a triple-clutch
transmission and a control system for permitting automatic shifting
of the triple-clutch transmission.
[0006] The automated triple-clutch multi-speed transmission of the
present invention is adapted to transfer power from the engine to
the driveline of a motor vehicle. The transmission includes an
output shaft adapted for connection to the driveline, an input
shaft continuously driven by the engine, a countershaft in constant
driving engagement with the output shaft, first, second and third
clutches, first, second and third constant mesh gearsets and first,
second and third gearset clutches. The first clutch is operable for
establishing a releasable drive connection between the input shaft
and a first shaft. The second clutch is operable for establishing a
releasable drive connection between the input shaft and a second
shaft. The third clutch is operable for establishing a releasable
drive connection between the input shaft and a third shaft. The
first constant mesh gearset is driven by the first shaft. The
second constant mesh gearset is driven by the second shaft. The
third constant mesh gearset is driven by the third shaft. The first
gearset clutch is operable for releasably drivingly coupling the
first gearset and the countershaft. The second gearset clutch is
operable for releasably drivingly coupling the second gearset and
the countershaft. The third gearset clutch is operable for
releasably drivingly coupling the third gearset and the
countershaft.
[0007] The automated triple-clutch transmission of the present
invention further includes fourth, fifth and sixth constant mesh
gearsets. The fourth constant mesh gearset is driven by the first
shaft and the first gearset clutch is operable for releaseably
drivingly coupling the fourth gearset and the countershaft. The
fifth constant mesh gearset is driven by the second shaft and the
second gearset clutch is operable for releaseably drivingly
coupling the fifth gearset and the countershaft. Finally, the sixth
constant mesh gearset is driven by the third shaft and the third
gearset clutch is operable for releaseably drivingly coupling the
sixth gearset and the countershaft. Accordingly, a six-speed
powershiftable transmission is provided.
[0008] Further areas of applicability will become apparent from the
description provided herein. It should be understood that the
description and specific examples are intended for purposes of
illustration only and are not intended to limit the scope of the
present disclosure.
DRAWINGS
[0009] The drawings described herein are for illustration purposes
only and are not intended to limit the scope of the present
disclosure in any way.
[0010] FIG. 1 is a schematic view of a triple-clutch automated
transmission as described in the disclosure;
[0011] FIG. 2 is a diagrammatic illustration of a transmission
control system adapted for use with the triple-clutch automated
transmission shown in FIG. 1; and
[0012] FIG. 3 is a cross-sectional view of the triple-clutch
automated transmission.
DETAILED DESCRIPTION
[0013] The following description is merely exemplary in nature and
is not intended to limit the present disclosure, application, or
uses. It should be understood that throughout the drawings,
corresponding reference numerals indicate like or corresponding
parts and features.
[0014] With reference to FIGS. 1-3 of the accompanying drawings, a
triple-clutch automated transmission, hereinafter referred to as
transmission 10, will now be described. Transmission 10 is driven
by the output of an engine 12 and generally includes a first clutch
14, a second clutch 16, a third clutch 18, an input shaft 20, a
first tubular shaft 22, a geartrain having a plurality of output
gearsets 24, a countershaft 26, a second tubular shaft 28, a third
tubular shaft 30, an output shaft 32, and a shift control system
34.
[0015] First clutch 14 is a multi-plate clutch having a plurality
of inner clutch plates 36 in splined engagement with a hub 37 fixed
to first tubular shaft 22. A plurality of outer clutch plates 38
are in splined engagement with a housing 40 fixed to an input stub
shaft portion 20A of input shaft 20. First clutch 14 is normally
operable in an engaged or closed state to establish a drive
connection between input shaft 20 and first tubular shaft 22. A
first power-operated actuator 42 can be selectively actuated to
apply a force to cause inner clutch plates 36 and outer clutch
plates 38 to separate from one another and cease the transfer of
torque through first clutch 14. In the embodiment shown, first
actuator 42 is a hydraulically-actuated device that controls the
magnitude of torque transferred through first clutch 14. As noted,
first actuator 42 may also fully release first clutch 14 so no
torque is transferred therethrough.
[0016] Second clutch 16 is a multi-plate clutch having a plurality
of inner clutch plates 50 in splined engagement with second tubular
shaft 28 and a plurality of outer clutch plates 52 in splined
engagement with a housing 54. Housing 54 includes a central
reaction ring 56 that is fixed to input shaft 20. Inner clutch
plates 50 and outer clutch plates 52 are free to axially move
between positions spaced apart from one another wherein second
clutch 16 does not transfer torque and positions wherein inner
clutch plates 50 frictionally engage outer clutch plates 52 and
torque is transferred between second tubular shaft 28 and input
shaft 20. Second clutch 16 is also a normally closed clutch that
transmits torque when not acted upon by an external force. A second
power-operated actuator 60 is operable to control actuation of
second clutch 16 to selectively transfer a predetermined quantity
of torque between input shaft 20 and second tubular shaft 28 or
fully release the clutch plates from one another.
[0017] Third clutch 18 shares housing 54 with second clutch 16. A
plurality of outer clutch plates 62 are in splined engagement with
housing 54. A plurality of inner clutch plates 64 are in splined
engagement with third tubular shaft 30. Outer clutch plates 62 and
inner clutch plates 64 are interleaved with one another to form a
clutch pack. Third clutch 18 is a normally closed clutch. A third
power-operated actuator 66 is operable to control actuation of
third clutch 18 to selectively disengage inner clutch plates 64
from outer clutch plates 62 and cease the transfer of torque
between input shaft 20 and third tubular shaft 30. While it is
contemplated that first actuator 42, second actuator 60 and third
actuator 66 are hydraulically operated devices, other types of
power-operated actuators including electrically-powered actuators
are within the scope of the present disclosure.
[0018] The plurality of constant mesh output gearsets 24 in the
geartrain include a first gearset 70 having a first drive gear 72
fixed to first tubular shaft 22 which is meshed with a first speed
gear 74 rotatably supported on countershaft 26. A second gearset 76
includes a second drive gear 78 fixed to second tubular shaft 28
which is in meshed engagement with a second speed gear 80 rotatably
supported on countershaft 26. A third gearset 82 includes a third
drive gear 84 fixed to third tubular shaft 30 which is in meshed
engagement with a third speed gear 86 rotatably supported on
countershaft 26. A fourth gearset 88 includes a fourth drive gear
90 fixed to first tubular shaft 22 which is in meshed engagement
with a fourth speed gear 92 rotatably supported on countershaft 26.
A fifth gearset 94 includes a fifth drive gear 96 fixed to second
tubular shaft 28 which is in meshed engagement with a fifth speed
gear 98 rotatably supported on countershaft 26. A sixth gearset 100
includes a sixth drive gear 102 fixed to third tubular shaft 30
which is in meshed engagement with a sixth speed gear 104 rotatably
supported on countershaft 26. A reverse gearset 106 includes a
reverse drive gear 108 fixed to first tubular shaft 22, a reverse
speed gear 110 rotatably supported on countershaft 26 and a reverse
idler gear 112 which is in meshed engagement with reverse drive
gear 108 and reverse speed gear 110. An output gearset 114 includes
a first output gear 116 fixed to output shaft 32 and in meshed
engagement with a second output gear 118 fixed to countershaft
26.
[0019] To provide a robust, compact package, first tubular shaft 22
is concentrically mounted on input shaft 20 and rotatably supported
thereon by suitable bearings between input shaft 20 and a
transmission case 44. Likewise, third tubular shaft 30 is
concentrically mounted on input shaft 20 and rotatably supported
thereon by suitable bearings between input shaft 20 and case 44.
Finally, second tubular shaft 28 is concentrically mounted and
rotatably supported between adjacent ends of input shaft 20 and
output shaft 32 via suitable bearings.
[0020] Shift control system 34 includes a plurality of
power-operated gearset clutches which are operable for selectively
coupling a selected speed gear to countershaft 26 for establishing
the six forward and one reverse speed ratio drive connections
between input shaft 20 and output shaft 32. Preferably, these
gearset clutches are electrically-actuated dog clutches. In
particular, a first dog clutch 130 is operable for selectively
coupling/releasing first speed gear 74 and fourth speed gear 92
to/from countershaft 26. A second dog clutch 132 is operable for
selectively coupling/releasing second speed gear 80 and fifth speed
gear 98 to/from countershaft 26. A third dog clutch 134 is operable
for selectively coupling/releasing third speed gear 86 and sixth
speed gear 104 to/from countershaft 26. A fourth dog clutch 136 is
operable for selectively coupling/releasing reverse speed gear 110
to/from countershaft 26. Each dog clutch includes a sliding sleeve
(denoted by the suffix "A") which is splined for rotation with and
axial movement on a clutch hub (denoted by the suffix "B") which,
in turn, is fixed to countershaft 26. As is conventional,
bidirectional axial movement of the sliding sleeves from neutral,
central uncoupled positions shown results in clutched engagement
with the adjacent speed gear. Each dog clutch may be electrically
powered to control axial movement of the shift sleeves. It is to be
understood that any other type of power-operated device capable of
moving each sliding sleeve between its uncoupled and coupled
positions is within the scope of this disclosure. FIG. 3 depicts
transmission 10 equipped with synchronized electrically-actuated
dog clutches. The synchronizers are identified with like numerals
having a suffix "prime" designation.
[0021] As best shown in FIG. 2, shift control system 34 includes a
controller 150 which receives various sensor input signals, denoted
diagrammatically by block 152. Transmission controller 150 is an
electronically-controlled unit capable of receiving data from the
vehicle sensors and generating output signals in response to the
sensor input signals. The input signals delivered to controller 150
can include, without limitation, engine speed, throttle position,
brake status, input shaft speed, tubular shaft speeds, countershaft
speed, and output shaft speed. Controller 150 is operable to
coordinate and monitor actuation of all the electrically-controlled
devices associated with shift control system 34, so as to permit
powershifted sequential and skip-shift gear changes automatically
without any input from the vehicle operator. As such, transmission
10 is capable of being smoothly shifted automatically without power
interruption.
[0022] If desired, a manually-operable mode selector switch 154 can
be provided to shift transmission 10 from its automatic shift mode
to a manual shift mode. Mode switch 154 would, when actuated, allow
the vehicle operator to manually shift available gearshift devices
(paddles, switches, etc.) to effect sequential gear shifts and
skip-shifts without the use of a clutch pedal. However, controller
150 would only permit the selective gear shift to be completed if
the current vehicle characteristics (i.e., engine speed, vehicle
speed, etc.) permit completion of the requested shift.
[0023] To operate the vehicle, engine 12 is started with the
gearshift lever in its PARK position. Each of first clutch 14,
second clutch 16 and third clutch 18 are in the normally engaged
state with their respective drive connections completed. However,
each of the electrically-actuated dog clutches are released with
each shift sleeve located in its neutral uncoupled position such
that no drive torque is delivered from input shaft 20 to
countershaft 26. When the vehicle operator moves the gearshift
lever from the PARK position to the DRIVE position, first actuator
42 is operated to place first clutch 14 in its open state. Dog
clutch 130 is then actuated to drivingly interconnect first speed
gear 74 and countershaft 26. Once first speed gear 74 is drivingly
coupled to countershaft 26, first actuator 42 is controlled to
allow normally closed first clutch 14 to transfer torque from input
shaft 20 to first tubular shaft 22. First clutch 14 is gradually
engaged to smoothly accelerate the vehicle.
[0024] Thereafter, controller 150 evaluates vehicle operating
parameters in an attempt to estimate the next most likely gear
ratio to be provided. If controller 150 indicates that a shift into
the second forward gear ratio is probable, controller 150 actuates
second actuator 60 to place second clutch 16 in its open condition.
At this time, second dog clutch 132 is actuated to drivingly engage
second speed gear 80 with countershaft 26. If controller 150
determines that a skip shift into the third forward gear ratio may
be more desirable, third actuator 66 operates to place third clutch
18 in its open condition. At this time, third dog clutch 134 is
actuated to drivingly couple third speed gear 86 to countershaft
26. One skilled in the art will appreciate that because controller
150 has pre-selected the second forward gear ratio and the third
forward gear ratio as possible targets, a mechanically efficient,
smooth and expeditiously executed shift may be completed into
either of these gears.
[0025] In particular, if a 1-2 shift is to occur, first clutch 14
is gradually disengaged while second clutch 16 is gradually
engaged. Power is continuously transferred to output shaft 32
during the 1-2 shift. Alternately, if a 1-3 skip shift is to occur,
first clutch 14 is gradually placed in the open condition while
third clutch 18 is gradually controlled to transfer torque. The 1-3
shift previously described is also a power shift where torque is
transferred to output shaft 32 at all times during execution of the
shift.
[0026] The gear and clutch arrangement of transmission 10 allows
controller 150 to preselect anticipated forward gear ratios to
prepare for additional clutch to clutch power shifts. For example,
if transmission 10 is presently operating in the fourth forward
gear ratio, torque is being transferred through fourth speed gear
92. First clutch 14 is in its closed, torque transferring condition
while second clutch 16 and third clutch 18 may be in their open or
closed states. To pre-select the probable gear ratios, second
clutch 16 and third clutch 18 are released. Second dog clutch 132
is actuated to drivingly couple fifth speed gear 98 to countershaft
26. At the same time, third dog clutch 134 is actuated to drivingly
couple third speed gear 86 to countershaft 26. Transmission 10 is
now prepared for a down-shift from the fourth forward gear ratio to
the third forward gear ratio, or an up-shift from the fourth
forward gear ratio to the fifth forward gear ratio. Either of these
shifts may be completed by a simple clutch-to-clutch shift similar
to the ones previously described. Specifically, a 4-3 down-shift
occurs by gradually disengaging first clutch 14 while gradually
engaging third clutch 18. A 4-5 up-shift may alternately be
completed by gradually disengaging first clutch 14 while gradually
engaging second clutch 16.
[0027] It should be appreciated that a wide variety of sequential
or skip shifts may be completed as simple clutch to clutch shifts
based on the grouping of various drive gears associated with each
clutch. For example, the Figures depict first clutch 14 operably
providing drive torque to reverse gearset 106, first gearset 70,
and fourth gearset 88. Second clutch 16 is operable to allow torque
transfer through second gearset 76 and fifth gearset 94. Finally,
third clutch 18 selectively transfers torque through third gearset
82 and sixth gearset 100. To best meet the expected shifting
scenarios, the pairings may be modified.
[0028] Transmission 10 is also operable in an energy conservation
mode when operating within any one of the speed ratios. If
controller 150 determines that transmission 10 has been operated in
a certain drive gear for a predetermined amount of time and that
the throttle position has changed only minimally, each of the dog
clutches associated with the speed gears not currently transferring
torque are moved to their normally centered position where a speed
gear is not coupled to countershaft 26. Furthermore, the two plate
clutches that are not transferring torque are allowed to return to
their normally closed positions. At this time, energy is not
required to be provided to any of first actuator 42, second
actuator 60 or third actuator 66. When transmission 10 is in the
energy conservation mode as previously described, the transmission
operates very similarly to a manual transmission as opposed to a
typical automatic transmission. Typical automatic transmissions
require energy to be continuously supplied to cause the interleaved
plates of the clutch packs to be forced into contact with one
another and transfer torque. The normally closed clutches of
transmission 10 alleviate the need for a supply of hydraulic
pressure or electrical energy to transfer torque at a predetermined
gear ratio.
[0029] From the following description, it should be apparent that
transmission 10 provides an energy efficient assembly where
sequential shifts are skip shifts may be pre-selected thereby
requiring only clutch switching to effect a shift. Benefits include
smoother, quicker sequential shifts as well as skip shifts.
Depending on the number of forward and reverse gear ratios desired,
various combinations of clutches and gearsets may be configured
even though not explicitly depicted in the drawings. These and
other variations disclose and describe merely exemplary embodiments
of the present invention. One skilled in the art will readily
recognize from such discussion, and from the accompanying drawings
and claims, that various changes, modifications and variations may
be made therein without department from the spirit and scope of the
invention as defined in the following claims.
* * * * *